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Unity Gameplay Layer: How Game Objects interact with graphisc sub-system

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I'm currently thinking about how to correctly design the GamePlay layer of my engine.
Here are the several class that compose it (only in my head by now !):

[size=2]- GameParameter
[size=2]A kind of Variant data used to store generic data like:
[size=2] -float, int vec2, vec3, bool

[size=2]- GameService
[size=2]A typical component used to control the various capability of a given GameObject like:
[size=2] - Renderable, GUI, Input ( and at the moment,that's all because i can't figured out other component type ... )

[size=2]- GameEvent
[size=2]An even like onMouseClicked() onUpdate() ...

[size=2]- GameObjectPrototype
[size=2]A definition of a game object containing :
[size=2] - a list of GameComponent
[size=2] - a list of GameParameter with default value
[size=2] - an instanciate method
[size=2]It also contain a script file (lua in my case) which is used to implement custom behavior of the object by responding to the various GameEvents, querying the GameServices and manipulating GameParameters

[size=2]- GameObject
[size=2]They are instance of a given GameObectPrototype including all the predefined GameComponent and GameParameter.

[size=2]- GameContext
[size=2]Contain a map of all the GameObjects

I'm pretty happy with this first draft, but i'm pretty sure i'll have to do a lot of adjustment in order to make it really usable.
Beside that, i have some questions concerning two main points:

First GameServices:
Like i said before, i actually cannot figured out any other interseting services.
I have looked at Unity game component which is really (great... and ) "fine grained":
For exemple there is Transformable Component, and a Renderable Component.
In my case i can't split component this way, because my Renderable Component will give the GameObject the ability to acces a whole Render Node including transformation informations.

So what's your opinion concerning the integration of a GameObject component system within a "Node based" render engine

Second GameEvent:
Does the type of GameEvent a given object is receiving depend upon the kind of components attached to this object ?

Once again, any opinion, or discussion are welcome !

Hope this will inspire you !!

Clément Vidal

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What you're describing as game services looks a lot like a component based model. Though I didn't really understand your "node based rendering" explanation.
you might want to check out http://en.wikipedia.org/wiki/Component-based_software_engineering as well as http://www.purplepwny.com/blog/?p=215.
I'm not a big fan of the component based model, 'cause I just find that it leads to a lot of classes and not much gained in terms of neatness or flexibility. Anyway, each to his own.

As for the second one, you'll probably have a layer that converts low level events to game events.
For example you might convert keyPress(KEY_W) to something like UNIT_MOVE_UP.
So, all the actual event handling is done by this "layer" and the high level game events are broadcasted throughout your system. A common way to do this is to use the Observer pattern, where all listeners register as "Observers" and another pushes events.

http://login2win.blogspot.in/2008/05/c-observer-patterm.html and http://www.codeproject.com/Articles/888/Applying-Observer-Pattern-in-C-Applications should get you started on the observer pattern.

Best of luck!

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